623 research outputs found
STRUCTURE AND DYNAMICS OF RADICALS IN SOLIDS BY EPR AND ENDOR SPECTROSCOPIES
No full textEPR and ENDOR (Electron Nuclear DOuble Resonance) spectroscopies give complementary information in the study of paramagnetic species in solids. The ENDOR technique allows the determination of hyperfine tensors an order of magnitude smaller with respect to the EPR one. The molecular motions in solids affect the relaxation of both the transverse and longitudinal magnetization of the paramagnetic probe. The measurement of the transverse relaxation time is traditionally available by the EPR Lineshape analysis. Population variations due to the longitudinal relaxation processes can be monitored by the study of the amplitude of the ENDOR spectra
Asymptotics of degrees and ED degrees of Segre products
No full textFunding Information: We thank Jay Pantone for very useful conversations. We thank the referees for useful comments. The first two authors are members of INDAM-GNSAGA. The third author would like to thank The Department of Mathematics of Universit? di Firenze, where this project started in June 2018, for the warm hospitality and financial support. The first author is supported by the H2020-MSCA-ITN-2018 project POEMA. The second author is partially supported by the Academy of Finland Grant 323416. The third author is supported by Vici Grant 639.033.514 of Jan Draisma from the Netherlands Organisation for Scientific Research. Publisher Copyright: © 2021 The Author(s)Two fundamental invariants attached to a projective variety are its classical algebraic degree and its Euclidean Distance degree (ED degree). In this paper, we study the asymptotic behavior of these two degrees of some Segre products and their dual varieties. We analyze the asymptotics of degrees of (hypercubical) hyperdeterminants, the dual hypersurfaces to Segre varieties. We offer an alternative viewpoint on the stabilization of the ED degree of some Segre varieties. Although this phenomenon was incidentally known from Friedland-Ottaviani's formula expressing the number of singular vector tuples of a general tensor, our approach provides a geometric explanation. Finally, we establish the stabilization of the degree of the dual variety of a Segre product X×Qn, where X is a projective variety and Qn⊂Pn+1 is a smooth quadric hypersurface.Peer reviewe
Electron Spin-lattice Relaxation-time and Spectral Diffusion In Gamma-irradiated L-alanine.
No full textWe performed continuous (CW) wave and pulsed ESR experiments to obtain information on the relaxation behavior of the 1-alanine radical in an irradiated single crystal. The analysis of the CW saturation behavior gives a relaxation time of 2.8 micro s. The echo detected saturation recovery was obtained for a number of different experimental conditions. In any case only a portion of the 120 G wide ESR spectrum can be affected by the microwave (MW) pulses, spectral diffusion is active and a multi-exponential decay is therefore obtained. We measured characteristic spectral diffusion times of 1-10 and 20-50 micro s. We found that a long time of about 200 micro s can be measured only by using a train of long selective saturating pulses and short detecting pulses. The stimulated echo decay is bi-exponential, and the characteristic times are very short. A variable temperature investigation in the range 200 to 290 K showed that the decay is governed by the spectral diffusion and by the transverse nuclear spin relaxation time T-2n of the methyl protons
CaCO3 Crystallite Evolution during CaO Carbonation: Critical Crystallite Size and Rate Constant Measurement by In-Situ Synchrotron Radiation X-ray Powder Diffraction
No full textSimulation of EPR and Time Resolved EPR lineshapes in partially ordered phases
No full textSimulation of magnetic resonance spectra of probes in partially ordered glasses requires in principle a numerical integration on the full set of three Euler angles Ohm=(alpha beta gamma) from a laboratory fixed to a molecule fixed reference frame. It is shown that it is possible to manage efficiently this problem by using the algebraic properties of the Wigner matrix elements. This analysis is applied to time resolved EPR (TREPR) spectra of a series of bis-adducts of C-60 in the ordered glass of a nematic liquid crystal solvent. A paramagnetic triplet state is created by light excitation and TREPR spectra are obtained with the external magnetic field set parallel or perpendicular to the director n of the mesophase. The preferred orientation in the mesophase of the triplet state zero field tensor is determined
Exhibiting Fashion Symposium: Simona Segre Reinach "Fashion Exhibitions in Italy"
No full textThe Museum at FIT presented Exhibiting Fashion, its twenty-first academic symposium on Friday, March 8, 2019. This symposium explored the history of fashion curating, the different ways fashion is displayed in museum settings, and how national and regional identities influence fashion exhibitions. The symposium was organized in conjunction with Exhibitionism: 50 Years of The Museum at FIT, which commemorated the rich history of the museum, the site of more than 200 exhibitions since the 1970s.Simona Segre Reinach is an associate professor of fashion studies at Bologna University. She recently organized the exhibition Jungle: The Imagery of Animals in Fashion and is the co-author of Exhibit! Showcasing Fashion: Exhibition Spaces and Brand Spaces
L’«appassionata ricerca del nuovo»: Mario Segre lettore del «Columbus» di Ubertino Carrara (1715)
No full textThis chapter aims to illustrate the method adopted by Mario Segre for the analysis of the Latin epic poem "Columbus" (1715), written by Ubertino Carrara, an author of the Accademia dell’Arcadia. Columbus is the subject of Segre’s first scientific monograph, published in 1925. In this volume, Segre applies a critical reading method based on a geographical perspective - justified by his pupillage with Paolo Revelli and the dialogue with the Geographical
Institute of Genova - and focuses on identifying the historical and literary sources Carrara used and reworked. Segre’s critical work looks at the poem as a historical and geographical testimony, at the beginning of the Eighteenth Century, of the knowledge about the New World territories and the voyages of Cristoforo Colombo
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